1. Field of the Invention
This invention relates to a camera for use in a photogrammetric analytical measurement, in which a survey map is produced on the basis of a set of photographed pictures obtained at two different photographing positions.
2. Description of the Related Art
For example, photogrammetry is carried out at a traffic accident spot. The traffic accident spot is photographed by a camera in at least two different positions, and a survey map of the traffic accident spot is produced based on a set of photographed pictures obtained at the different positions.
In particular, a two-dimensional coordinate system is defined on each of the photographed pictures, and two-dimensional positions of the objects, which are recorded on each picture, are determined by the two-dimensional coordinate system. Then, a three-dimensional coordinate system is defined on the basis of the two sets of two-dimensional coordinate systems, and three-dimensional positions of the recorded objects are determined from the three-dimensional coordinate system. Accordingly, it is possible to produce a survey map of the traffic accident spot by drawing the objects on a sheet of paper in such a manner that the objects are projected on one of the three planes defined by the three-dimensional system.
Before accurately scaled distances and lengths can be reproduced on the survey map, a standard measurement scale must be recorded together with the objects in the photographed pictures. Also, a standard reference plane, on which the survey map should be drawn, must be defined in the photographed pictures.
Usually, in order to define the standard measurement scale and the reference plane, three respective cone-shaped markers, which are identical to each other, are positioned at suitable locations around a traffic accident spot. Namely, a distance between two apexes of the cone-shaped markers is measured, for example, with a measuring tape, and set as the standard measurement scale, and a plane, defined by the three apexes of the cone-shaped markers, is utilized as the reference plane.
Before the three-dimensional positions of the objects can be determined using the three-dimensional coordinate system, a relative-positional relationship between the photographing positions should be derived from the three-dimensional coordinate system. Nevertheless, a very circuitous and convoluted process is required to calculate the relative-positional relationship between the photographing positions. For this reason, conventionally, the relative-positional relationship between the photographing positions is obtained by iterating approximate calculations using a computer. However, use of an iterative process creates a protracted survey map development time.
Therefore, an object of the present invention is to provide a camera for use in a photogrammetric analytical measurement, performing photography at each photographing position, which is provided with a relative-position-detecting system for deriving a relative-positional relationship between the different photographing positions.
In accordance with an aspect of the present invention, there is provided a camera for use in a photogrammetric analytical measurement, performing photography at a photographing position, comprising a relative-position-detecting system for three-dimensionally detecting a relative-positional relationship between different photographing positions.
Preferably, the relative-position-detecting system is associated with a three-dimensional coordinate system defined in the camera such that an origin of the three-dimensional coordinate system is situated at a suitable position with respect to the camera, and is constituted so as to detect the relative-positional relationship between the different photographing positions with respect to the three-dimensional coordinate system. The suitable position may be a back principal point of the camera.
Preferably, the three-dimensional coordinate system has a first axis extending vertically with respect to the Earth, and second and third axes extending horizontally from the origin of the three-dimensional coordinate system so as to be perpendicular to each other.
The relative-position-detecting system may comprise three respective rotational-angle sensors for detecting rotational-angular movement data around the first, second and third axes of the three-dimensional coordinate system, and three respective acceleration sensors for detecting acceleration data along the first, second and third axes of the three-dimensional coordinate system. Preferably, one of the three rotational-angle sensors for detecting the rotational-angular movement around the first axis of the three-dimensional coordinate system comprises a magnetic azimuth sensor.
The relative-position-detecting system may further comprise a first calculator for calculating relative-three-dimensional angular data between the different photographing positions on the basis of the rotational-angular movement data detected by the rotational-angle sensors at the different photographing positions, and a second calculator for calculating relative-three-dimensional translational movement data between the different photographing positions on the basis of the acceleration data detected by the acceleration sensors at the different photographing positions. The relative-position-detecting system may further comprise a third calculator for calculating relative-three-dimensional positional data between the different photographing positions on the basis of the relative-three-dimensional translational movement data calculated by the second calculator.
Furthermore, the camera may further comprise a detachable memory medium for storing image data photographed by the camera, along with the relative-three-dimensional angular data and the relative-three-dimensional positional data.
With executing a photographing operation at two different consecutive photographing positions, the relative-position-detecting system may further comprise a fourth calculator for calculating differential-angular data with respect to two consecutive relative-three-dimensional angular data derived from the different photographing positions, and a fifth calculator for calculating differential-positional data with respect to two consecutive relative-three-dimensional positional data derived from the different photographing positions. In this case, preferably, the detachable memory medium further stores the differential-angular data, and the differential-positional data. On the other hand, the detachable memory medium may stores the image data photographed by the camera, together with the differential-angular data and the differential-positional data in place of the relative-three-dimensional angular data and the relative-three-dimensional positional data.
In accordance with another aspect of the present invention, there is provided a memory medium storing image data, photographed by a camera, and relative-three-dimensional angular data and relative-three-dimensional positional data, which specify an photographing position of the camera.
Preferably, in the memory medium, the relative-three-dimensional angular data and the relative-three-dimensional positional data are associated with a three-dimensional coordinate system defined in the camera. An origin of the three-dimensional coordinate system may be situated at a suitable position with respect to the camera. Also, preferably, the three-dimensional coordinate system has a first axis extending vertically with respect to the Earth, and second and third axes extending horizontally from the origin of the three-dimensional coordinate system so as to be perpendicular to each other.
The memory medium may further store differential-angular data, generated from two consecutive relative-three-dimensional angular data derived from different consecutive photographing positions at which is executed, and differential-positional data, generated from the two consecutive relative-three-dimensional positional data derived from the different consecutive photographing positions.
In accordance with yet another aspect of the present invention, there is provided a memory medium storing image data photographed by a camera, together with differential-angular data, obtained with respect to two consecutive relative-three-dimensional angular data derived from different consecutive photographing positions at which a photographing operation is executed, and differential-positional data, obtained with respect to two consecutive relative-three-dimensional positional data derived from the different consecutive photographing positions.
Preferably, in this memory medium, the differential-angular data and the differential-positional data are associated with a three-dimensional coordinate system defined in the camera. An origin of the three-dimensional coordinate system is situated at a suitable position with respect to the camera. Also, preferably, the three-dimensional coordinate system has a first axis extending vertically with respect to the Earth, and second and third axes extending horizontally from the origin of the three-dimensional coordinate system so as to be perpendicular to each other.